1. Field of the Invention
The present invention is directed to a vented ink reservoir for facilitating gaseous communication between an interior of an ink reservoir and an external environment; and, more particularly to a vented ink reservoir utilizing a semipermeable membrane to enable the ingress and/or egress of gas with respect to an interior volume of the ink reservoir, where the ink reservoir includes a backpressure regulator housed therein that prevents weeping from one or more printhead nozzles in fluid communication therewith.
2. Background of the Invention
Inkjet pens consist of a jetting structure and an ink containing structure. These structures can be combined into a single integrated cartridge, or separated into tanks and printheads. In either situation, the ink that is fed to the jetting structure must be kept at a negative pressure with respect to pressure outside the pen to prevent the ink from running out of the pen due to gravity, also known as weeping.
Several methods are known for the control of this negative pressure, also known as “backpressure”. In some inkjet structures the backpressure is provided by capillary action from a foam sponge, while other structures seal up the system and use a regulation device or a bubble-generating device to allow air to replace spent ink within the system while maintaining a reasonable range of backpressures. Still further systems are sealed off and start at a moderate backpressure and increase in backpressure until the jetting device can no longer pull ink from the reservoir.
Prior art techniques have attempted to control backpressure by providing a collapsible bag acting as the reservoir. The volume of the bag decreases in proportion to the volume of ink leaving the reservoir. However, these collapsible bags require multiple seals and have been found to be problematic to fabricate.